1. Field of the Invention
This invention relates to a novel thiol ester having utility as a sleep-inducing agent, an antibacterial agent and an acylating agent for amines and hydrazines, particularly as active esters for preparing cephalosporin compounds, a process for their preparation and a process for the preparation of cephalosporin compounds using the thiol esters.
2. Description of the Prior Art
An 1,3,4-thiadiazole-5-thiol ester of the formula, ##STR3## where R is a hydrogen atom or a methyl group, and a process for its preparation have not been reported yet.
Further, heretofore, any method is not known for preparing a cephalosporin compound of the formula, ##STR4## wherein R is hydrogen atom or a methyl group, by one step using 7-aminocephalosporanic acid or its derivative as the starting material. In order to obtain the above described cephalosporin compound, it is necessary to employ the methods as described in U.S. Pat. Nos. 3,278,531 and 3,516,997, Japanese Patent Publication Nos. 5150/1971 and 35751/1971 as a combination. For example, the above described cephalosporin compound may be prepared by two steps, i.e., either by firstly reacting 7-aminocephalosporanic acid with 1H-tetrazole-1-acetic acid and secondly reacting the 7-(1H-tetrazol-1-ylacetamido)-cephalosporanic acid thus obtained with an 1,3,4-thiadiazole-5-thiol or by firstly reacting 7-aminocephalosporanic acid with an 1,3,4-thiadiazole-5-thiol and secondly reacting the 7-amino-3-(1,3,4-thiadiazol-5-yl)-thiomethyl-3-cephem-4-carboxylic acid thus obtained with 1H-tetrazole-1-acetic acid. Thus, these methods require two-step operation, and further a separation procedure such as an extraction with a solvent for recovering the unstable product formed in the first step and, as a result, the yield is too low for practical purposes.